State Department spokesman Sean McCormack declined to overtly criticize Zalmay Khalilzad, the ambassador at the United Nations, for joining a panel at the World Economic Forum with Iranian Foreign Minister Manochehr Mottaki.

But McCormack said his appearance there had not been authorized by the State Department and a similar arrangement would not be repeated unless Iran reverses course on its disputed nuclear program.

"Is there some new policy, ... was permission asked for in advance? No, it's not a new policy. There wasn't any permission in advance," he said.

It apears that Khalilzad stuck to the US policy line, he added.

"I don't think that he said anything different there than one might say from the podium or an interview with the media," he said.

Asked if it would have been better for Khalizad to have avoided such an event, McCormack said it was a one-off incident.

"You can judge by the fact we haven't done these sorts of things in the past, and I don't expect that we will, absent some agreement from the Iranians that they are going to suspend their uranium enrichment processing and reprocessing related activities," he said.

"There are channels through which we communicate with the Iranians," he said.

The US government communicates with the Iranians through the Swiss Embassy and US ambassador Ryan Crocker in Baghdad, he recalled.

"And there is a potential secretary of state channel should they chose to suspend their enrichment," he added.

Standing US protocol requires US diplomats "to be polite but don't have any substantive interaction" if they run into an Iranian government official in a professional or social situation, McCormack said.

But he declined to say whether he thought Khalilzad had a "substantive" encounter.

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